1. Technical Field
The invention relates generally to managing electromagnetic radiation, and more particularly, to a device and method for managing electromagnetic radiation having a frequency in the terahertz and/or microwave ranges.
2. Background Art
The terahertz range of frequencies corresponds to frequencies between three hundred gigahertz (GHz) and thirty terahertz (THz). This range lies in between the frequency ranges of electronic devices (that typically operate at frequencies below three hundred GHz) and photonic devices (that typically operate at frequencies above five to thirty THz). For example, the upper frequency that can be attained using an electronic transistor is typically limited by the transit time of carriers under the gate (for a field effect transistor) or across the base and collector depletion region (for a bipolar junction transistor). The feature sizes of some of these devices, such as silicon metal oxide semiconductor field effect transistors (MOSFETs), compound semiconductor heterostructure field effect transistors (HFETs), and heterojunction bipolar transistors, can be scaled to obtain device parameters into the terahertz range (i.e., transistor operation at frequencies of a few hundred GHz). However, fundamental physics limitations, such as the size of the gate length versus the wave length of the terahertz radiation, limit the extent of the device scaling and the transit time limited regimes face are not effective for the terahertz range of frequencies. Photonic devices also have been created that approach the terahertz gap using interband or intersubband transitions. However, these devices must operate at cryogenic temperatures due to the smaller quanta of terahertz radiation versus thermal energy at room and liquid nitrogen temperatures.
Plasma wave oscillations (which are oscillations of electron density in time and space) and their possible uses continue to be explored. Plasma waves for a field effect transistor have also been analyzed. To this extent, infrared absorption and weak infrared emission related to such waves have been observed in silicon inversion layers. More recently, studies of high mobility AlGaAs/GaAs gated heterostructures revealed the resonance impedance peaks related to the plasma waves. Further, one study used hydrodynamic equations to analyze plasma waves in 2D electron gas and predicted the instability of plasma waves in a high mobility field effect transistor.
Some studies are now focusing on plasma wave electronic devices, such as detectors and mixers. One such study reported evidence of resonant plasma wave detection by a field effect transistor at the third harmonic. More recently, other studies have reported resonant plasma wave detection at the fundamental harmonic by a field effect transistor and in multi-gated periodic structures with 2D electron gas.
Two difficulties must be overcome to use plasma waves for terahertz oscillators, detectors, mixers, and multipliers. First, highly non-symmetrical boundary conditions, e.g., an open drain and short-circuited source, are required for efficient operation. Second, since the plasma wave velocity is much smaller than the light velocity and device dimensions are much smaller than the electromagnetic wave length that corresponds to the plasma frequency, antenna structures are needed for coupling plasma waves and electronic waves. However, these antenna structures are much larger than typical devices. To this extent, the coupling of the antenna structures for electromagnetic radiation and the integration of a device with sub-millimeter circuits needs to be addressed for the implementation of practical plasma wave devices. These issues, and the antenna and circuit design, have been investigated for submicron Schottky diodes operating in the terahertz range.
To this extent, a need exists for a solution that overcomes these limitations. In particular, there exists a need for a device and method for managing radiation, such as terahertz and/or microwave radiation, using plasma wave oscillations.